Hi, I have a 2016 1.25L fiesta and wondering the total hp amount i could add to the engine without compromising the reliability too much and blowing up the engine. and what engine modifications (with product company names) would be recommended to maximise hp.  thanks. 

It’s a small NA engine. There really isn’t much you can do with it. Tyres, brakes and suspension would add much more beneficial performance over anything to the engine. 

As Alex has said your starting with a small na engine so the not much to be gotten. Just get an enormous exhaust and pod filter for the placebo effect

Assuming you have the 82 ps version, a Superchips (or similar) remap will get you a small increase in power/torque for around £250 at present: https://www.superchips.co.uk/ECU-Remap/Ford/Fiesta-Mk7-2008/Petrol/Style-1-25-81-bhp/stage-1 

If you have the rarer 60ps version a remap can bring this up to 80 or so, so probably worthwhile in that case.

If you really want to throw a lot of time, money and effort at it see this thread:

 

Stick a Puma 1.7 in👍

To get the full potential out of that wee' engine always go for it down a steep hill 🤣😂🤣

thinking of just doing a stage 1 adding 11bhp to make it 93bhp with induction kit, new exhaust, coilovers and possibly intercooler? 

11bhp gain is not worth the cost of a remap.

Also no point fitting an intercooler to a non turbo engine, it'll just cause more of a restriction than before and reduce power.  You can fit a cold air feed to an NA engine but honestly power mods aren't worth the cost on this engine.  Better off going for looks and noise instead.